Cell Therapeutics appeals FDA decision

Cell Therapeutics has submitted a formal appeal to the US FDA challenging the federal agency's negative decision on the company's investigational treatment for non-Hodgkin's lymphoma

Cell Therapeutics has submitted a formal appeal to the US Food and Drug Administration (FDA) challenging the federal agency's negative decision on the company's investigational treatment for non-Hodgkin's lymphoma (NHL).

The appeal, filed with the Office of New Drugs in the FDA's Center for Drug Evaluation and Research, argues that the FDA improperly analysed a late-stage clinical trial of the drug pixantrone for relapsed/refractory aggressive NHL. In a Complete Response Letter issued to the company in April, the FDA's Office of Oncology Drugs said that it would require an additional clinical trial before the drug could be approved because the study submitted in the New Drug Application (NDA), known as PIX301, did not demonstrate efficacy.

The NDA for pixantrone is seeking marketing clearance through the FDA's accelerated approval programme, under which drugs that meet urgent unmet medical needs can be approved based on surrogate endpoints.

Cell Therapeutics noted that it already had plans in place for another clinical trial before it received the Complete Response Letter. The additional trial, known as PIX306, was planned by the company to serve as either a post-approval confirmatory trial or a second registration trial for approval. However, the company nonetheless objects to the conclusion that the PIX301 trial failed to demonstrate efficacy and argues that the decision was made based on faulty practices.

The company asserts that the FDA applied a stringent statistical significance level that is intended to be used if an interim analysis has been conducted, which was not the case with the pixantrone trial, in which only a final analysis was undertaken. "We believe the results of the PIX301 clinical trial should be analysed with the appropriate threshold that is standard for trials of this type in which only one efficacy analysis was conducted," said Richard Kay of the School of Pharmacy, Cardiff University, who is serving as a consultant for the company on the matter.

Cell Therapeutics said it expects a decision on the appeal in the first quarter of 2011. Meanwhile, the company is preparing for the second trial and has filed a Marketing Authorisation Application with the European Medicines Agency (EMA), which was accepted for review on November 17.